disease outbreak infection many people within a short period of time.
first case in an epidemic
disease that is always present in a population at roughly the same level
interview cases to find similarities
interview controls to find out differences
used to identify the source of the epidemic
prevention of epidemics due to scarcity of susceptible hosts (non vaccinated are protected by those who are vaccinated)
most need to be immune/vaccinated. (germ cant spread)
Herd Immunity in Japan
influenza in Japan
school-aged had to be vacc. protect old people
caused mortality rates to drop.
cases increased when vacc. stopped
common source v propagated
common: food, water
propagated: one individual starts epidemic